You know that the false flag operation theory makes no sense at all given the course of the war and it's duration.
Presumably if you were going to do some evil **** like that you would want to have military strength at it's optimal level of performance.
The most baffling thing about the false flag theory is: why would anyone (as in, the author of that pamphlet) even consider it? The fact he did is one of my reasons do believe that Orlais indeed tried invading first - after all, even not knowing anything you wouldn't be thinking about RC being a false-flag to have a pretext for invasion if no invasion followed. But, as we know - if the invasion took place (and I, for reasons stated before, believe it did) it was promptly beaten back. That's not what happens when a powerful nation pre-prepares its military for an invasion they're going to provide a pretext for themselves...
Basically, Orlais making a false-flag operation doesn't add up even just based on the knowledge the author must've had. The least dubius claim he could've had in mind would be a false-flag but not conducted by Orlais, but by some petty noble or a bunch of rogue zealots. Then it would make (a bit) more sense since such people wouldn't necessarily think straight, could greatly underestimate the Dales and could, potentially, decide to just start a war, convinced that the war would surely be won (even if they themselves had no authority to prepare the army the war needed). So - I think perhaps this is what was going through the author's head...
Either way, in light of our current knowledge (with Elandrin's death memorial), I consider false flag operation one of those crazy fan theories. Sure, I could let my imagination run loose and create more-or-less consistent scenario, but what for, really, when we have an account of real conflict with likely at least some dead bodies... no third party proceeding to slaughter the rest of townsfolk to put the blame of the elves is necessary to explain what happened - so Ockham's Razor says: put it on the tinfoil hat shelf.